diff --git a/layout/base/AccessibleCaretManager.cpp b/layout/base/AccessibleCaretManager.cpp
index 35cd3979fc01..3fb066d305b8 100644
--- a/layout/base/AccessibleCaretManager.cpp
+++ b/layout/base/AccessibleCaretManager.cpp
@@ -99,9 +99,9 @@ AccessibleCaretManager::HideCarets()
 void
 AccessibleCaretManager::UpdateCarets(UpdateCaretsHint aHint)
 {
-  mCaretMode = GetCaretMode();
+  mLastUpdateCaretMode = GetCaretMode();
 
-  switch (mCaretMode) {
+  switch (mLastUpdateCaretMode) {
   case CaretMode::None:
     HideCarets();
     break;
@@ -402,7 +402,7 @@ AccessibleCaretManager::OnScrollStart()
 void
 AccessibleCaretManager::OnScrollEnd()
 {
-  if (mCaretMode != GetCaretMode()) {
+  if (mLastUpdateCaretMode != GetCaretMode()) {
     return;
   }
 
@@ -418,7 +418,7 @@ AccessibleCaretManager::OnScrollEnd()
 void
 AccessibleCaretManager::OnScrollPositionChanged()
 {
-  if (mCaretMode != GetCaretMode()) {
+  if (mLastUpdateCaretMode != GetCaretMode()) {
     return;
   }
 
@@ -429,7 +429,7 @@ AccessibleCaretManager::OnScrollPositionChanged()
 void
 AccessibleCaretManager::OnReflow()
 {
-  if (mCaretMode != GetCaretMode()) {
+  if (mLastUpdateCaretMode != GetCaretMode()) {
     return;
   }
 
diff --git a/layout/base/AccessibleCaretManager.h b/layout/base/AccessibleCaretManager.h
index d0814f133b93..6aad8822c4d9 100644
--- a/layout/base/AccessibleCaretManager.h
+++ b/layout/base/AccessibleCaretManager.h
@@ -115,7 +115,10 @@ protected:
     // appearance to Normal.
     RespectOldAppearance
   };
+  // Update carets based on current selection status.
   void UpdateCarets(UpdateCaretsHint aHint = UpdateCaretsHint::Default);
+
+  // Force hiding all carets regardless of the current selection status.
   void HideCarets();
 
   void UpdateCaretsForCursorMode(UpdateCaretsHint aHint);
@@ -182,8 +185,12 @@ protected:
   // The caret being pressed or dragged.
   AccessibleCaret* mActiveCaret = nullptr;
 
+  // The timer for hiding the caret in cursor mode after timeout behind the
+  // preference "layout.accessiblecaret.timeout_ms".
   nsCOMPtr<nsITimer> mCaretTimeoutTimer;
-  CaretMode mCaretMode = CaretMode::None;
+
+  // The caret mode since last update carets.
+  CaretMode mLastUpdateCaretMode = CaretMode::None;
 
   static const int32_t kAutoScrollTimerDelay = 30;
 };